Document VOLTHA Resources

resources/docker.rst
resources/repositories.rst
--------------------------
  o Added a resources/ section in docs.voltha.org.
  o Display links for docker URLs and gerrit/github repositories.
  o rst table generation is partly automated using a list of resource
    names and a makefile target that can generate line items.
  o This logic should be built out so docker.rst and resources.rst
    can be fully auto-generated.
  o resources::gerrit repository urls have been populated in the table.
    Strange: url syntax is fine (matches manual navigation), gitiles is
    able to digest the url but only displays a white screen.  Might be
    missing a cookie or context the UI passes.  Will debug this later.

Change-Id: I71ed0e3760ed597707a0abaf35b2e07a68e14ed7
diff --git a/index.rst b/index.rst
index c57e9ee..3dd6fa7 100644
--- a/index.rst
+++ b/index.rst
@@ -205,6 +205,14 @@
    release_notes/index.rst
 
 .. toctree::
+   :maxdepth: 1
+   :hidden:
+   :caption: Resources
+   :glob:
+
+   resources/index
+
+.. toctree::
    :maxdepth: 2
    :caption: HOWTO Topics